In the development of computer based tools, one significant concern is the interface between the computer and the human user, i.e. the "man-machine" interface. Early computer man-machine interfaces were entirely character based, which required a user to type in the individual commands that made the computer perform such tasks as opening a document, storing a document, deleting a document, etc. Character based interfaces require a user to have a high degree of computer literacy in order to use each command properly and as such are non-intuitive and unforgiving in that each command must be typed according to the proper syntax, without a mistake, before the command will be executed by the computer. The MS-DOS.RTM. operating system by Microsoft is an example of such a character based man-machine interface.
A significant advance over the character based interface was the icon based interface, which provided a symbol on the screen of the computer to represent a particular action or application. In a typical icon based interface, a number of icons are displayed on a computer screen. A user performs a task, such as executing a program, by selecting the icon with an input or pointing device, for example, with a computer mouse. After selecting the icon with the mouse, a window typically appears on the screen. The user then uses the program by typing in the window. If the user wishes to execute another program, another icon is selected, which in turn opens another window on the screen. The use of a computer mouse greatly facilitated the icon based interface, as well as reducing the use of a keyboard. The Windows.RTM. operating system by Microsoft is an example of such an icon based man-machine interface.
The most recent advance in man-machine interface is the use of touch screens. A touch screen allows a user to directly control a program through direct contact, either by finger or stylus, with the computer screen. The direct interaction provided by a touch screen eliminates the need for a mouse. Thus, the use of touch screens provides the user with an extremely desirable man-machine interface. A detailed description of touch screen technology is provided in U.S. Pat. No. 4,897,511 to Itaya et al.
Another advance in computer technology is the provision of multi-media presentations. Multi-media is a term that generally describes audio-visual related computer applications and may include digitally stored video images (such as frames from film footage or, alternatively, still photographs). Multi-media, when combined with touch screen technology, can be used to provide a navigable video environment to a user. As is known by those skilled in the art, a navigable video environment attempts to emulate visually to a user a predetermined environment such that the user can navigate that environment. In simpler terms, an effective navigable environment is "just like being there."
Prior art attempts at creating a realistic navigable video environment have been met with mixed success. Perhaps the most successful of such navigable video environments has been the "Virtual Museum" project jointly developed by Apple Computer, Inc., the Massachusetts Institute of Technology, and the University of Regina in Canada. The Virtual Museum is a computer based rendering of a museum which contains objects of interest that can be individually examined. The user can interactively move through the museum, via input from a touch screen, and selectively pull up and view certain objects from a variety of perspectives. A complete description of the Virtual Museum project can be found in The Virtual Museum: Interactive 3D Navigation of a Multimedia Database, Miller et al.
One deficiency of the Virtual Museum, however, is that the user is only able to view one level of video environment. For example, the user cannot move through the Virtual Museum and also control a second level video environment being played on a television object within the Virtual Museum.